Sneaker Trends

These Running Shoes Are Made From Captured Carbon Emissions

Photo: On Running
Running shoes are typically pretty terrible for the environment. Made with synthetic materials, the average pair has a carbon footprint of about 30 pounds of carbon dioxide equivalent, according to one study. And since the ever-growing athletic footwear market is expected to produce 625.98 million pairs by 2025, that’s a major impact on our planet.

But On Running is working to reverse this trend. The brand recently developed the first shoe made from carbon emissions—basically turning industrial pollution into foam for running shoes.

How does it work?

The first step is capturing industrial carbon emissions that would normally go out into the atmosphere. “Instead of the gases going up a kind of chimney stack, there's essentially a pipeline that pipes the gas into this big vessel,” says Freya Burton, chief sustainability officer of LanzaTech, a carbon recycling company that On partnered with for this process. In this case, the industrial facility is a steel mill in China.

Then LanzaTech uses gas fermentation—similar to the fermentation process for beer, but instead of using sugars, it uses the carbon in the emissions, Burton explains. “We pump the gas into this reactor, which has got our microbes in it, and water and some basic things like vitamins and other things that they need to grow.” The carbon gets fermented and produces liquid ethanol.

Next, the company Technip Energies dehydrates the ethanol so that it becomes ethylene gas. Then Borealis, a circular and renewable plastic solutions company, polymerizes that ethylene to make EVA pellets. The result is a high-performance material On calls CleanCloud.

This development helps On move away from fossil fuels in its materials. But it may also signal new possibilities for transforming carbon pollution into usable materials.

“We envision a future where every On product is fossil-free and is engineered for circularity,” says Ilmarin Heitz, head of global innovation at On. “Our mission is to make high-performance products with the lowest possible footprint.”

Building a better shoe

Although running shoes are sometimes recycled into playground materials, “the options for recycling of sneakers are pretty limited,” Burton says.

“Shoe production is challenging in terms of sustainable material choice,” says Mathilde Charpail, the founder of Sustain Your Style, a platform to inform fashion consumers, and SANE STANDARD, a holistic certification for fashion products. But running shoe manufacturers have started to incorporate other innovative materials that reduce their carbon footprint, including EVA foam made from algae, she notes.

And On has created a circular subscription service called Cyclon for some of its shoes that are recyclable.

“Holding the first-ever shoe made of carbon emissions in my hands is a huge milestone—not only for On, but for the whole sports industry. Five years ago, this was barely a dream,” Heitz says. It took those years to find the right partners and figure out how to make each step in the process doable—and at a commercial scale.

“One of the biggest questions was how to overcome the challenge of scaling a promising new technology for mass production,” Heitz says. “We realized we needed to build a new supply chain. This is quite a big undertaking and long-term investment.”

The shoe is called the Cloudprime. CleanCloud™ EVA foam is used in the midsole, and, through a partnership with French start-up Fairbrics, the polyester-based textile in the upper is also made from carbon emissions. Part of the midsole also contains 40 percent bio-based thermoplastic polyurethane (TPU), made from castor beans, and the outsole is 35 percent upcycled TPU, through a collaboration with the chemicals company Novoloop.

The potential impact

Some apparel already contains similar technology. Zara, for instance, partnered with LanzaTech to create two collections that also used captured carbon emissions, and they sold out within hours, Burton says. That might be a signal that consumers have an appetite for these types of products.

Burton notes that other companies in the carbon transformation space are doing related work. “There's so much more out there in terms of recycling carbon,” she says.

But apparel and footwear are “kind of forgotten sectors. The apparel sector has a bigger carbon footprint than the aviation sector,” Burton says. With this development, “what we're trying to show here is that there are new ways of making the materials that are in our daily life.”

So will buying a pair of running shoes made from recycled carbon emissions actually do much for the environment?

Answering this question requires “understanding how much energy is being used in order to take the carbon emissions to do the fermentation process into ethanol and then making the EVA,” says Yuly Fuentes-Medel, project manager for fiber technologies at the MIT Materials Research Laboratory. It depends on whether this process uses less energy than the processes already being used to make EVA.

“I think we are in the beginning of understanding: How are we going to use the excess of CO2 into consumer products?” Fuentes-Medel says. Any company that works “to invest in technologies that are going to make their products more sustainable is something we should celebrate—but also keep them accountable for the amount of energy that this replacement is creating.”

Also, although Charpail isn’t familiar with the Cloudprime technology, she says that with some other promising innovations in sustainable materials, “digging deeper, I realized that only 20 percent, 30 percent, or 40 percent of the material was made of the ‘innovative’ ingredient and the rest was still virgin synthetic material.”

About the Cloudprime technology overall, Charpail says, “The concept is great. It solves several issues at once: transforming carbon emissions into something else than pollution and replacing synthetic material, made from petrol.”

In gauging the impact of putting captured emissions into a shoe, consumer behavior is another consideration, Fuentes-Medel points out. “Everyone uses shoes, so therefore, you are impacting also our behavior,” she says. “You can make consumers part of the equation, which is something we haven't been able to achieve.”

The Cloudprime shoe isn’t available for sale yet, but the company says it will be in the near future, and it aims to keep the price within the current range of On’s running shoes.

“If we want a better future," says Heitz, "we have to be willing to build it."

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